Merge pull request #649 from the-luap/fix/branding-customcss-preset-drop-645

fix(branding+whatsapp): preserve customCss through preset switches (#645) + admin-pinned WhatsApp template language (#647)

backend/migrations/core/137_add_whatsapp_template_language.js

@@ -0,0 +1,31 @@
+/**
+ * Migration 137: WhatsApp template language (#647).
+ *
+ * Adds a `template_language` column to `whatsapp_configs` so admins can
+ * pin their Meta-approved template's language code (e.g. `ar`, `en_US`,
+ * `de_DE`) directly in Settings → WhatsApp. Without this column the only
+ * resolution paths were per-message `data.language` (always null in our
+ * own callers) and `app_settings.general_default_language` — both of
+ * which are tied to the *system* UI language, not the *template's* language
+ * registered with Meta. Reporter @Rekoo-PS hit this with an Arabic
+ * template against the test-send route.
+ *
+ * Additive + hasColumn-guarded. Empty string default means "fall through
+ * to general_default_language" — preserves current behaviour for installs
+ * that don't set it.
+ */
+exports.up = async function (knex) {
+  if (!(await knex.schema.hasTable('whatsapp_configs'))) return;
+  if (await knex.schema.hasColumn('whatsapp_configs', 'template_language')) return;
+  await knex.schema.alterTable('whatsapp_configs', (table) => {
+    table.string('template_language', 20).notNullable().defaultTo('');
+  });
+};
+
+exports.down = async function (knex) {
+  if (!(await knex.schema.hasTable('whatsapp_configs'))) return;
+  if (!(await knex.schema.hasColumn('whatsapp_configs', 'template_language'))) return;
+  await knex.schema.alterTable('whatsapp_configs', (table) => {
+    table.dropColumn('template_language');
+  });
+};